Disdrometer having acoustic transducer and methods thereof

ABSTRACT

An acoustic disdrometer is provided for measuring precipitation. The acoustic disdrometer has an acoustic transducer positioned within an acoustic chamber defined by an acoustic shell. Precipitation impacting the acoustic shell generates sound waves that are collected by the acoustic transducer for processing.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/452,457, filed on Mar. 7, 2017, entitled DISDROMETER HAVING ACOUSTICTRANSDUCER AND METHODS THEREOF, which claims the benefit of U.S.provisional patent application Ser. No. 62/305,211, filed on Mar. 8,2016, entitled, DISDROMETER HAVING ACOUSTIC TRANSDUCER AND METHODSTHEREOF, the disclosures of which are hereby incorporated by referencein their entirety.

TECHNICAL FIELD

Embodiments of the technology relate, in general, to disdrometers, andin particular to disdrometers comprising one or more acoustictransducers.

BACKGROUND

The accurate measurement of rainfall presents a great engineeringchallenge with large social impact. A wide range of measurement gaugescan be used, each having various limitations. Accumulation measurementmethods are the most common due to low cost and simple operatingprocedures. However, these methods have shortcomings in that they canaccumulate debris (including hail and snow) that require maintenance,can be poorly calibrated, can suffer from wind-induced losses, canhaving moving parts that prevent them from being mounted innon-stationary environments, and can be bulky to ship and install. Dropcounting methods have various advantages, in that they do not accumulatedebris, which reduces maintenance, have no moving parts, which expandsthe locales where these can be mounted, and can be more compact, whichreduces shipping and installation burden. These devices have additionalbenefits, in that they can distinguish rain from hail, can be used tocalibrate Doppler radar with the so-called “Z-factor” measured as aweighted sum of the drop sizes, and thus can be used to interpretrainfall over a broader spatial domain. Devices using drop countingmethods, however, can be power demanding and expensive, especiallyoptical-based drop counting devices that utilize a laser formeasurement.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be more readily understood from a detaileddescription of some example embodiments taken in conjunction with thefollowing figures:

FIG. 1 depicts a simplified block diagram of an example acousticdisdrometer in accordance with a non-limiting embodiment.

FIG. 2 depicts a simplified block diagram of another example acousticdisdrometer in accordance with a non-limiting embodiment.

FIG. 3 depicts a top view of an example acoustic disdrometer inaccordance with a non-limiting embodiment.

FIG. 4 is a bottom view of the example acoustic disdrometer shown inFIG. 3.

FIG. 5 is a side view of the example acoustic disdrometer shown in FIG.3.

FIG. 6 is an isometric view of the example acoustic disdrometer shown inFIG. 3.

FIG. 7 is a cross-sectional view of the example acoustic disdrometershown in FIG. 3 taken along line 7-7.

FIG. 8 is an exploded isometric view of the example acoustic disdrometershown in FIG. 3 with an acoustic shell separated from a housing of theacoustic disdrometer.

FIG. 9 is a chart plotting frequency (Hz) vs. power (dB) for exampledroplet diameters in accordance with one non-limiting embodiment.

FIG. 10 is a chart plotting droplet diameter (mm) vs. peak power (dB).

FIG. 11 is a chart plotting rainfall across a period of time inaccordance with one non-limiting embodiment.

FIG. 12 depicts a linear regression for data measured by an acousticdisdrometer in accordance with the present disclosure.

FIG. 13 is a chart plotting drop size distributions in accordance withone non-limiting embodiment

FIG. 14 is a quantile plot of reference laser disdrometer (X axis) andacoustic power distribution of an acoustic disdrometer (Y axis) inaccordance with one non-limiting embodiment.

DETAILED DESCRIPTION

Various non-limiting embodiments of the present disclosure will now bedescribed to provide an overall understanding of the principles of thestructure, function, and use of the apparatuses, systems, methods, andprocesses disclosed herein. One or more examples of these non-limitingembodiments are illustrated in the accompanying drawings. Those ofordinary skill in the art will understand that systems and methodsspecifically described herein and illustrated in the accompanyingdrawings are non-limiting embodiments. The features illustrated ordescribed in connection with one non-limiting embodiment may be combinedwith the features of other non-limiting embodiments. Such modificationsand variations are intended to be included within the scope of thepresent disclosure.

Reference throughout the specification to “various embodiments”, “someembodiments”, “one embodiment”, “some example embodiments”, “one exampleembodiment”, or “an embodiment” means that a particular feature,structure, or characteristic described in connection with any embodimentis included in at least one embodiment. Thus, appearances of the phrases“in various embodiments”, “in some embodiments”, “in one embodiment”,“some example embodiments”, “one example embodiment”, or “in anembodiment” in places throughout the specification are not necessarilyall referring to the same embodiment. Furthermore, the particularfeatures, structures or characteristics may be combined in any suitablemanner in one or more embodiments.

Some acoustic disdrometers in accordance with the present disclosure canbe relatively low maintenance and have low power consumption.Disdrometers in accordance with the present disclosure can utilize oneor more acoustic transducers, such as a micro electro-mechanical system(MEMS) microphones or condenser-type microphones, for example, forprecipitation measurement based on acoustic signals generated by theprecipitation's kinetic force impact and propagated through the air.This approach is in contrast to impact-type disdrometers that usepiezo-type or pressure force transducers for measuring signalspropagating through a solid. The approach utilized by acousticdisdrometers in accordance with the present disclosure is also incontrast to other types of acoustic disdrometers that may rely onmicrophones to measure signals propagating through a liquid, forinstance.

Example acoustic disdrometers in accordance with the present disclosurecan facilitate calculation of a rainfall rate directly from thefrequency (v) and power (P) of the received acoustic signal generated byindividual drops within a time interval:

R=Σ_(i=0) ^(N) f(v _(i) , P _(i))   EQ. 1

where R is the rainfall rate (mm/hr), N are the total number of drops,and f(v,P) is a mathematical function that could take one of many formsincluding but not limited to linear regression.

Example acoustic disdrometers in accordance with the present disclosurecan also enable calculation of drop sizes directly:

D _(i) =g(v _(i) , P _(i))   EQ 2

where g(v,P) is a mathematical function to calculate a drop size D fromfrequency and power. Such an estimate allows calculation of R from themeasured D distribution:

$\begin{matrix}{R = {\sum\limits_{i = 0}^{N}{\frac{4}{3}{\pi \left( \frac{D_{i}}{2} \right)}^{3}}}} & {{EQ}.\mspace{14mu} 3}\end{matrix}$

One advantage of estimating the drop size distribution D_(i) is tofacilitate calculation of a radar reflectivity factor (Z), as providedby EQ. 4:

Z=∫₀ ^(D) ^(max) N ₀ e ^(−ΛD) D ⁶ dD,   EQ. 4

where N is the number of drops (m⁻³), D is the diameter of drops (mm),and the resultant Z is in units mm⁶m⁻³. This formula can be used in thederivation of rainfall intensity from radar using an assumedrelationship between Z and rainfall rate. As such, any errors in theassumed drop size distribution and the actual drop size distributionresults in errors in the rainfall rate estimated by radar.

In some embodiments, a solar panel array can be incorporated into theacoustic disdrometer. The solar panel array can be mounted internal tothe device, as to protect it from the elements and can reduce the totalsize of the device. Additionally or alternatively, the solar panel arraycan be mounted external to the device, as may be necessary based oncertain mounting environments, for instance. Certain embodiments caninclude wired or wireless communications for data sharing so thatrainfall calculations or other types of calculations can be performed bya remote computing system (i.e., a cloud-based system) or a data streamfor data visualization can otherwise be provided by the disdrometer to arecipient data ingestion system.

FIG. 1 depicts a simplified block diagram of an example acousticdisdrometer 100 in accordance with one non-limiting embodiment. Theacoustic disdrometer 100 can have a housing 104 that interfaces with anacoustic shell 102, such as around its perimeter, and houses variouscomponents and at least partially defines one or more cavities orchambers within the acoustic disdrometer 100. The acoustic shell 102 canbe oriented such that it will be impacted by precipitation and generatesound waves having a frequency profile and amplitude profilecorresponding to various forms and rates of various precipitation types.The acoustic shell 102 can be generally planar, as depicted in FIG. 1,or it can be generally curved or rounded (i.e. domed shaped), asdepicted in FIG. 2, or have any other suitable configuration. Theacoustic shell 102 can be made from any suitable materials, such aspolycarbonate, or other plastic materials. In some embodiments, theouter surface of the acoustic shell 102 can have hydrophobic coating toassist with rainfall shedding. In some embodiments, at least part of theacoustic shell 102 can be transparent, or otherwise allow light rays topenetrate through the acoustic shell 102, as described in more detailbelow.

Portions of the housing 104 and an inner surface of the acoustic shell102 can cooperate to define an acoustic chamber 120 located interior tothe acoustic disdrometer 100. As shown, the acoustic shell can have anouter surface 102A and an inner surface 102B, with at least a portion ofthe inner surface 102B defining the air-filled acoustic chamber 120. Anacoustic transducer 106 can be positioned within the acoustic chamber120 to translate the impact of precipitation (rain, hail, etc.) on anouter surface of the acoustic shell 102 into a signal readable by acontrol unit 112 for signal processing. As such, the impact ofprecipitation of the outer surface 102B vibrates the acoustic shell 102to generate sound waves that propagate through the acoustic chamber 120and that are picked up by the acoustic transducer 106. The acoustictransducer 106 can be, for example, a micro electro-mechanical system(MEMS) microphone having an integrated analog to digital converter thatis positioned at or near the center of the acoustic chamber 120. In someembodiments, the acoustic transducer 106 is a microphone suitable forembedded applications (e.g. cellular telephones). In some embodiments,the acoustic transducer can be a condenser-type microphone that providesan analog signal that is digitized by a separate chip. As individualdrops of rain, hail, or sleet impact the acoustic shell 102, theacoustic transducer 106 generates corresponding signals for processingby a control unit 112. As discussed in more detail below,characteristics of the signals (such as power and frequency) can be usedto determine precipitation amounts.

In some embodiments, onboard power generation techniques are utilized.As shown in FIG. 1, the acoustic disdrometer 100 can comprise a solararray 108. The solar array 108 can be configured to generate power tosatisfy some or all of the power consumption requirements of theacoustic disdrometer 100. The solar array 108 can be in communicationwith a charge controller 110 which can include, for example, a maximumpower point controller or voltage regulator. In some embodiments,onboard power storage sources can be utilized (i.e., solar-chargedbattery cells, etc.).

In the illustrated embodiment, the acoustic shell 102 is transparent, orat least partially transparent or translucent, and the solar array 108is positioned internal to the acoustic chamber 120. In otherembodiments, the solar array 108 is positioned external to the acousticchamber 120. In such embodiments, the acoustic shell 102 may benon-transparent or at least partially non-transparent. As illustrated inFIGS. 3, 6, and 8, in some embodiments the solar array 108 can begenerally circular having an outer diameter similar to the outerdiameter of the acoustic shell 102, although this disclosure is not solimited. The acoustic transducer 106 can be positioned in the center ofthe solar array 108, such that the solar array 108 generally forms aring around the acoustic transducer 106. The control unit 112 and/orother modules of the acoustic disdrometer 100 can be powered based onvoltage generated by the solar array 108.

In some configurations, the acoustic disdrometer 100 can includeadditional on-board sensors, schematically depicted as sensor(s) 134.Data received from sensors associated with the acoustic disdrometer 100can be used to measure, crop water demand (using shortwave and longwaveradiation, humidity, air temperature, and crop and sky temperature), andamong others. The acoustic disdrometer 100 can also include a datainput/output module 114. The data I/O module 114 can include, forexample, one or more wireless communication radios or modules to supportvarious wireless communication protocols (i.e., Wifi-based protocols,LTE or GSM protocols, Bluetooth protocols, near field communicationprotocols, satellite protocols, cellular protocols, etc.). In someembodiments, the data I/O module 114 can also provide for wiredinterfaces, such as a USB-interface, Ethernet-interface, and so forth.In some operational environments, the acoustic disdrometer 100 cangenerally function as a weather monitor to enable various data-intensivenatural resource management or civil infrastructure management softwareservices. Furthermore, the acoustic disdrometer 100 can include GPS forsynthesizing with other geospatial data.

The data I/O module 114 can be used by the acoustic disdrometer 100 totransmit data to a data collection server in real-time, substantiallyreal-time, or in batch format. Additionally or alternatively, the dataI/O module 114 can be used by the acoustic disdrometer 100 to receivedata from one or more sensors 134, such as sensors for measuring soilmoisture, air quality, water pressure and flow, electrical current, andso forth. Additionally or alternatively, the sensor 134 can in includespectrometer(s), an accelerometer, among other sensors or datacollection instruments or systems. Additional tools, such as soilmoisture and salinity monitoring devices, a camera, or equipmentmonitors can be interface with one or more ports of the data I/O module114.

FIG. 2 depicts a simplified block diagram of another example acousticdisdrometer 200 in accordance with one non-limiting embodiment. Theacoustic disdrometer 200 can have a housing 204 that interfaces with anacoustic shell 202 to define an acoustic chamber 220. In thisembodiment, the acoustic shell 202 has a dome shape that can aid inwater shedding. The outer perimeter of the acoustic shell 202 can becircumscribed by a rib 230 to acoustically isolate it from othermechanical components. The rib 230 can be received into a correspondinggroove 232 on the housing 204. Various other technical for acousticisolation can be used, such as an O-ring, or other dampening devices.The size and shape of the acoustic shell 202, as well as its attachmenttechnique to the housing 204, can vary. In some embodiments, theacoustic shell 202 is circular and has a diameter of more than about 50cm. In some embodiments, the acoustic shell 202 is circular and has adiameter of less than about 50 cm. In some embodiments, the acousticshell 202 is circular and has a diameter of less than about 40 cm. Insome embodiments, the acoustic shell 202 is circular and has a diameterof less than about 20 cm. In some embodiments, the acoustic shell 202 iscircular and has a diameter of less than about 10 cm. In someembodiments, the acoustic shell 202 is circular and has a diameter ofabout 13.75 cm. Further, in some embodiments the acoustic shell 202 isabout 1 mm thick. In some embodiments the acoustic shell 202 is about1.5 mm thick. In some embodiments the acoustic shell 202 is about 2 mmthick. In some embodiments, the acoustic shell 202 can be made of metaland can be less than 1 mm thick. Depending on the configuration of theacoustic shell 202, it may be thicker at the edges where it meets thehousing 204. In embodiments utilizing a curved acoustic shell 202, thecurvature can be equivalent to a spherical radius of less than about 70cm. In embodiments utilizing a curved acoustic shell 202, the curvaturecan be equivalent to a spherical radius of less than about 60 cm. Inembodiments utilizing a curved acoustic shell 202, the curvature can beequivalent to a spherical radius of less than about 50 cm. Inembodiments utilizing a curved acoustic shell 202, the curvature can beequivalent to a spherical radius of less than about 40 cm.

The position of the acoustic transducer 206 within the acoustic chamber220 to can be selected to achieve desired performance. In someembodiments, the acoustic transducer 206 is positioned approximately ½radius distance away from the center of the dome of the acoustic shell202. In some embodiments, the acoustic transducer 206 is positionedapproximately ⅛ radius distance away from the center of the dome. Insome embodiments, the primary vibrational mode of the acoustic shell 202can be about 440 Hz. In some embodiments, the primary vibrational modeof the acoustic shell 202 can be about 550 Hz. In some embodiments, theprimary vibrational mode of the acoustic shell 202 can be about 660 Hz.Beneficially, the frequency of the primary vibrational mode can be abovetraffic noise (approx. 125 Hz) and below airplane noise (approx. 2000Hz) and is of a frequency within the human-perceptive range that istypical of many widely available consumer grade microphones.

Similar to FIG. 1, the acoustic shell 202 can be transparent to allowfor a solar array 208 positioned within the acoustic chamber 220 to beexposed to sunlight. The solar array 208 can be in communication with acharge controller 210. The acoustic disdrometer 200 can further comprisean acoustic transducer 206, control unit 212, sensor(s) 234, and a dataI/O module 214, similar to FIG. 1.

The acoustic disdrometer 200 in FIG. 2 schematically depicts a chamberthat is at least partially separated from the acoustic chamber 220,shown as dead air chamber 222. In the illustrated embodiment, the deadair chamber 222 is separated from the acoustic chamber 220 by a physicalbarrier 228, such that the acoustic chamber 220 is backed by the deadair chamber 222. In some embodiments, the physical barrier 228 can allowfor airflow between the acoustic chamber 220 and the dead air chamber222 through a port 262. The dead air chamber 222 can serve to generallyisolate the acoustic chamber 220 from potential sources of noise, thusincreasing the signal to noise ratio (SNR). The physical barrier 228shown in acoustic disdrometer 200 comprises the solar array 208, butadditional or alternative types of physical barriers can be used, suchas a printed circuit board positioned within the housing 204, forexample. A secondary acoustic transducer 216 can be positioned withinthe dead air chamber 222 to generate additional signals for processing.The signals received by the control unit 212 from secondary acoustictransducer 216 can be used to remove common mode noise such asmachinery, wind, or voices, included in the signal received from theacoustic transducer 206, thereby seeking to improve the signal to noiseperformance of the acoustic disdrometer 200. Thus, the secondaryacoustic transducer 216 can collect sounds that do not originate fromthe rain drops hitting the acoustic shell 202, but would otherwise bepresent in the signal of the acoustic transducer 206 in the acousticchamber 220, i.e. common-mode acoustic noise. Analysis of this secondstream of data from the secondary acoustic transducer 216 by the controlunit 212, or other associated processor, can allow the common modeacoustic noise (i.e., ambient noise) to be eliminated, or at leastreduced, which can further increase the SNR of the acoustic disdrometer.

The acoustic disdrometer 200 depicted in FIG. 2 also schematicallydepicts a housing 260 that is configured to totally or at leastpartially surround the acoustic transducer 206. In some embodiments, thehousing 260 is generally puck-shaped. The housing 260 can be configuredto function as a support structure to prevent dome collapse. The housing260 can rest on the physical barrier 228, which in turn is supported bya structure that is integral to the bottom of the dead air chamber 222.This structural configuration can add considerable strength againstimpact which might otherwise damage the acoustic shell 202.

Another example acoustic disdrometer 300 is depicted in FIGS. 3-8 inaccordance with a non-limiting embodiment. FIG. 3 depicts a top view,FIG. 4 depicts a bottom view, FIG. 5 depicts a side view, FIG. 6 is anisometric view, FIG. 7 is a cross-sectional view taken along line 7-7 inFIG. 3, and FIG. 8 is an exploded view. Referring to FIGS. 3-8, theacoustic disdrometer 300 can have a housing 304 that interfaces with anacoustic shell 302 to define an acoustic chamber 320. As shown in FIG.3, the acoustic shell 302 in the illustrated embodiment is transparentto allow for a solar array 308 mounted within the acoustic chamber 320to be exposed to sunlight. The example acoustic disdrometer 300 includesa dead air chamber 322, as depicted in FIG. 3. Similar to the acousticdisdrometer 200 of FIG. 2, the dead air chamber 322 is separated fromthe acoustic chamber 320 by a physical barrier 328, such that theacoustic chamber 320 is backed by the dead air chamber 322. Similar toFIG. 2, the acoustic disdrometer 300 depicted in FIGS. 3-8 alsocomprises a housing 330 that is configured to surround an acoustictransducer 306. Further, a secondary acoustic transducer 316 is shownpositioned within the dead air chamber 322. While the housing 330 isillustrated as being generally cylindrically-shaped, this disclosure isnot so limited. The acoustic disdrometer 300 also includes an auxiliaryport 340. The auxiliary port 340 can allow connectivity between theacoustic disdrometer 300 and one or more devices.

In some embodiments, the auxiliary port 340 can receive data fromauxiliary sensors. In some embodiments, the auxiliary port 340 canreceive power from an external DC source or solar panel. In someembodiments, the auxiliary port 340 can be used to transmit data usingmeans that are not present in the main device embodiment.

On-board sensors can provide additional data inputs to the system. Inthe illustrated embodiment, the acoustic disdrometer 300 isschematically shown to include shortwave and longwave spectral sensors372, a cellular modem 374, an accelerometer 376, and a GPS 378 (FIG. 7).The sensors can be used to provide additional data to improve theaccuracy and/or performance of the acoustic disdrometer 300. Forinstance, the accelerometer 378 can assist with the correction ofmechanical vibration. While these components are schematically shownbeing attached to the physical barrier 328, it is to be appreciated thatany of these components can be located at other internal or externalpositions. Further, in some embodiments, acoustic disdrometer 300 cancomprise a wetness detector such that power requirements of the devicecan be reduced by avoiding the use of the control until necessaryconditions (e.g. wetness) are met.

As shown in the illustrated embodiment, the acoustic disdrometer 300 caninclude a vented zone 360. The vented zone 360 can house various sensors334, such as an air temperature sensor, a humidity sensor, barometricpressure sensor, and the like. The vented zone 360 can be positioned inany suitable location. In the illustrated embodiment zone 360 protrudesfrom an undersurface 305 of the housing 304 can allow for air flowproximate to the sensors 334. The acoustic disdrometer 300 depicted inFIG. 3 also comprises a mounting assembly 350. While the mountingassembly 350 is shown to facilitate mounting the acoustic disdrometer300 to a post, other mounting assemblies can be used.

Acoustic disdrometers in accordance with the present disclosure convertdrop impact of an acoustic shell in into an acoustic signal. Based onlocal or remote processing of the acoustic signal, precipitation rates,drop size distributions, identifications of rain and hail, among otherprecipitation-related parameters can be determined. FIG. 9 is a chart900 plotting acoustic frequency (Hz) vs. acoustic power (dB) for exampledroplet diameters dropped onto an acoustic shell from a distance of 29feet. FIG. 10 is an example chart 1000 plotting droplet diameter (mm)vs. Peak power (dB). To generate the data presented in FIG. 9 and FIG.10, sounds generated by the kinetic force impact of water drops wererecorded with a commercial-off-the-shelf (COTS) MEMS microphonemeasuring sound from 20 Hz-20 kHz. As shown in FIG. 9, the observeddrops show a peak at 440 Hz, with high signal strength for even thesmallest drop size used in the test (2 mm). The power of the peak atthis frequency also shows a strong linear relationship with dropdiameter, as depicted in FIG. 10. Raw rainfall rate can be calculated asthe sum of the volume of all drops falling in some period of time,divided by area of the acoustic shell and time. For dome-shaped acousticshells, the effective area of the acoustic shell can be about 72%, forexample, depending upon the curvature of the dome and total diameter.The Z-factor of the rainfall can be calculated by summing the measureddrop diameter counts raised to the 6th power in some volume. In someembodiments, a library of acoustic waveforms can be utilized to identifyand flag spurious signals generated by the acoustic disdrometers, as maybe generated from machinery, voices, wind. Such a library can bedeveloped, for example by machine learning algorithms that cancategorize signals, such as by types of sounds.

FIG. 11 depicts a chart 1100 plotting an example rainfall across aperiod of time. The plot 1100 includes data 1102 which is representativeof a rainfall rate over the period of time. The data 1104 isrepresentative of the measured rainfall rate as measured by an acousticdisdrometer in accordance with the present disclosure. For the datapresented in chart 1100, the root mean square error (RMSE) is 1.1118mm/hr and the coefficient of determination (R2) is 0.82838.

Referring now to FIG. 12, a chart 1200 depicts a linear regression 1202for data measured by an acoustic disdrometer in accordance with thepresent disclosure between acoustic rainfall rate (X axis) versusreference rainfall rate (Y axis).

FIG. 13 is a chart 1300 plotting drop size distributions 1302, 1304.Drop size distribution 1302 is measured by a laser disdrometer and dropsize distribution 1304 is measured by an acoustic disdrometer inaccordance with the present disclosure.

FIG. 14 is a chart 1400 is a quantile plot of reference laserdisdrometer (X axis) and acoustic power distribution of an acousticdisdrometer (Y axis) in accordance with the present disclosure. Chart1400 illustrates one potential transfer function from drop sizedistribution to acoustic power distribution.

The examples discussed herein are examples only and are provided toassist in the explanation of the apparatuses, devices, systems andmethods described herein. None of the features or components shown inthe drawings or discussed below should be taken as mandatory for anyspecific implementation of any of these the apparatuses, devices,systems or methods unless specifically designated as mandatory. For easeof reading and clarity, certain components, modules, or methods may bedescribed solely in connection with a specific figure. Any failure tospecifically describe a combination or sub-combination of componentsshould not be understood as an indication that any combination orsub-combination is not possible. Also, for any methods described,regardless of whether the method is described in conjunction with a flowdiagram, it should be understood that unless otherwise specified orrequired by context, any explicit or implicit ordering of stepsperformed in the execution of a method does not imply that those stepsmust be performed in the order presented but instead may be performed ina different order or in parallel.

In general, it will be apparent to one of ordinary skill in the art thatat least some of the embodiments described herein can be implemented inmany different embodiments of software, firmware, and/or hardware. Thesoftware and firmware code can be executed by a processor or any othersimilar computing device. The software code or specialized controlhardware that can be used to implement embodiments is not limiting. Forexample, embodiments described herein can be implemented in computersoftware using any suitable computer software language type, using, forexample, conventional or object-oriented techniques. Such software canbe stored on any type of suitable computer-readable medium or media,such as, for example, a magnetic or optical storage medium. Theoperation and behavior of the embodiments can be described withoutspecific reference to specific software code or specialized hardwarecomponents. The absence of such specific references is feasible, becauseit is clearly understood that artisans of ordinary skill would be ableto design software and control hardware to implement the embodimentsbased on the present description with no more than reasonable effort andwithout undue experimentation.

Moreover, the processes described herein can be executed by programmableequipment, such as computers or computer systems and/or processors.Software that can cause programmable equipment to execute processes canbe stored in any storage device, such as, for example, a computer system(nonvolatile) memory, an optical disk, magnetic tape, or magnetic disk.Furthermore, at least some of the processes can be programmed when thecomputer system is manufactured or stored on various types ofcomputer-readable media.

It can also be appreciated that certain portions of the processesdescribed herein can be performed using instructions stored on acomputer-readable medium or media that direct a computer system toperform the process steps. A computer-readable medium can include, forexample, memory devices such as diskettes, compact discs (CDs), digitalversatile discs (DVDs), optical disk drives, or hard disk drives. Acomputer-readable medium can also include memory storage that isphysical, virtual, permanent, temporary, semipermanent, and/orsemitemporary.

A “computer,” “computer system,” “host,” “server,” or “processor” canbe, for example and without limitation, a processor, microcomputer,minicomputer, server, mainframe, laptop, personal data assistant (PDA),wireless e-mail device, cellular phone, pager, processor, fax machine,scanner, or any other programmable device configured to transmit and/orreceive data over a network. Computer systems and computer-based devicesdisclosed herein can include memory for storing certain software modulesused in obtaining, processing, and communicating information. It can beappreciated that such memory can be internal or external with respect tooperation of the disclosed embodiments. The memory can also include anymeans for storing software, including a hard disk, an optical disk,floppy disk, ROM (read only memory), RAM (random access memory), PROM(programmable ROM), EEPROM (electrically erasable PROM) and/or othercomputer-readable media. Non-transitory computer-readable media, as usedherein, comprises all computer-readable media except for a transitory,propagating signals.

In various embodiments disclosed herein, a single component can bereplaced by multiple components and multiple components can be replacedby a single component to perform a given function or functions. Exceptwhere such substitution would not be operative, such substitution iswithin the intended scope of the embodiments.

The foregoing description of embodiments and examples has been presentedfor purposes of illustration and description. It is not intended to beexhaustive or limiting to the forms described. Numerous modificationsare possible in light of the above teachings. Some of thosemodifications have been discussed, and others will be understood bythose skilled in the art. The embodiments were chosen and described inorder to best illustrate principles of various embodiments as are suitedto particular uses contemplated. The scope is, of course, not limited tothe examples set forth herein, but can be employed in any number ofapplications and equivalent devices by those of ordinary skill in theart.

We claim:
 1. An acoustic disdrometer, comprising an acoustic shellhaving a top surface and a bottom surface, wherein the bottom surfacedefines an acoustic chamber; a control unit; a first acoustic transducerpositioned within the acoustic chamber, wherein the first acoustictransducer is configured to provide acoustic signals to the control unitin response to precipitation impacting the top surface of the acousticshell; and a dead air chamber at least partially defined by the housing.2. The acoustic disdrometer of claim 1, further comprising a secondacoustic transducer, wherein the acoustic transducer is configured toprovide acoustic signals to the control unit.
 3. The acousticdisdrometer of claim 2, wherein the control unit is to configured removecommon mode noise based on the acoustic signals provided by the secondacoustic transducer.
 4. The acoustic disdrometer of claim 3, wherein thesecond acoustic transducer is positioned within the dead air chamber. 5.The acoustic disdrometer of claim 1, further comprising a port disposedbetween the acoustic chamber and the dead air chamber.
 6. The acousticdisdrometer of claim 1, wherein the first acoustic transducer comprisesa micro electro-mechanical system microphone.
 7. The acousticdisdrometer of claim 1, wherein at least a portion of the acoustic shellis translucent.
 8. The acoustic disdrometer of claim 7, furthercomprising a solar array, wherein the solar array is in electricalcommunication with the control unit.
 9. The acoustic disdrometer ofclaim 8, wherein the solar array is positioned within the acousticchamber.
 10. The acoustic disdrometer of claim 9, wherein at least aportion of the solar array is positioned between the acoustic chamberand the dead air chamber.
 11. The acoustic disdrometer of claim 1,wherein the top surface of the acoustic shell is planar.
 12. Theacoustic disdrometer of claim 1, wherein the top surface of the acousticshell is domed shaped.
 13. An acoustic disdrometer, comprising anacoustic shell having a top surface and a bottom surface, wherein atleast a portion of the acoustic is translucent; an acoustic chamberdefined at least partially by the acoustic shell; a control unit; anacoustic transducer positioned within the acoustic chamber, wherein theacoustic transducer is configured to provide acoustic signals to thecontrol unit in response to precipitation impacting the top surface ofthe acoustic shell; and a solar array positioned within the acousticchamber, wherein the solar array is in electrical communication with thecontrol unit.
 14. The acoustic disdrometer of claim 13, wherein thesolar array surrounds the acoustic transducer.
 15. The acousticdisdrometer of claim 13, wherein the acoustic transducer comprises amicro electro-mechanical system microphone.
 16. A method of measuringprecipitation, comprising: receiving, by a control unit associated withan acoustic disdrometer, an acoustic signal generated by a primaryacoustic transducer responsive to liquid or solid precipitation directlyimpacting at a plurality of locations across the surface area ofacoustic shell of the acoustic disdrometer, wherein the liquid or solidprecipitation directly impacting the acoustic shell comprises naturallyvarying individual drop sizes; determining, by the control unit, anacoustic frequency (Hz) and an acoustic power (dB) of the acousticsignal corresponding to the individual drops of liquid or solidprecipitation and determining, by the control unit, a rate ofprecipitation based at least in part on frequency and acoustic power ofthe acoustic signal and the surface area of the acoustic shell.
 17. Themethod of claim 16, further comprising: determining, by the controlunit, a diameter distribution of the precipitation based on a transferfunction relating frequency and acoustic power to drop size,
 18. Themethod of claim 16, wherein the rate of precipitation is based at leastin part on the sum of a volume of droplets falling over a period oftime.
 19. The method of claim 16, further comprising: determining, bythe control unit, a radar reflectivity factor based at least in part ona sum of the droplet diameters.
 20. The method of claim 16, furthercomprising: receiving, by the control unit, an acoustic signal generatedby a secondary acoustic transducer of the acoustic disdrometer; andremoving, by the control unit, common mode noise from the acousticsignal received from the primary acoustic transducer based on the secondacoustic signal.
 21. The method of claim 16, wherein the control unit ispositioned within the acoustic disdrometer.
 22. The method of claim 16,further comprising: discriminating, by the control unit, liquidprecipitation and solid precipitation based on distinguishing featuresof the acoustic frequency (Hz) and an acoustic power (dB) of theacoustic signal.
 23. The method of claim 16, further comprising:identifying, by the control unit, spurious acoustic signals based ondistinguishing features of acoustic frequency (Hz) and an acoustic power(dB) of the acoustic signal, wherein the spurious acoustic signals arecaused by any of machinery, voices, or wind.
 24. A method of measuringprecipitation, comprising: receiving, by a control unit associated withan acoustic disdrometer, an acoustic signal generated by a primaryacoustic transducer responsive to individual drops of precipitationimpacting an acoustic shell of the acoustic disdrometer, wherein theindividual drops vary in drop size; determining, by the control unit, anacoustic frequency (Hz) and an acoustic power (dB) of the acousticsignal corresponding to the individual drops of precipitation; anddetermining, by the control unit, a rate of precipitation based at leastin part on frequency and acoustic power of the acoustic signal.
 25. Themethod of claim 24, wherein the rate of precipitation is based at leastin part on the sum of a volume of droplets falling over a period oftime.
 26. The method of claim 16, further comprising: receiving, by thecontrol unit, an acoustic signal generated by a secondary acoustictransducer of the acoustic disdrometer; and removing, by the controlunit, common mode noise from the acoustic signal received from theprimary acoustic transducer based on the second acoustic signal.
 27. Themethod of claim 24, wherein the control unit is positioned within theacoustic disdrometer.
 28. The method of claim 24, further comprising:discriminating, by the control unit, liquid precipitation and solidprecipitation based on distinguishing features of the acoustic frequency(Hz) and an acoustic power (dB) of the acoustic signal.
 29. The methodof claim 24, further comprising: identifying, by the control unit,spurious acoustic signals based on distinguishing features of acousticfrequency (Hz) and an acoustic power (dB) of the acoustic signal,wherein the spurious acoustic signals are caused by any of machinery,voices, or wind.
 30. The method of claim 24, further comprising:powering the control unit by a solar array.